diff -r e598d1acf354 -r 56b48961cc68 controls/DebugVariablePanel/GraphButton.py
--- a/controls/DebugVariablePanel/GraphButton.py	Fri Sep 22 20:12:22 2017 +0300
+++ b/controls/DebugVariablePanel/GraphButton.py	Thu Sep 28 12:20:40 2017 +0300
@@ -31,7 +31,7 @@
 # -------------------------------------------------------------------------------
 
 
-class GraphButton():
+class GraphButton(object):
     """
     Class that implements a custom button for graphic Viewer
     """